1. Field of the Invention
The present invention relates to an improvement in a vehicle helmet, including a cap body comprised of a shell and a shock absorbing liner fitted in the shell, and a longitudinal air duct which extends in a wall of of the cap body, such that the interior of the cap body can be ventilated through the air duct.
2. Description of the Prior Art
There is such a helmet conventionally known, for example, from Japanese Patent Publication No. 1118/74, which includes an air duct formed in a groove-like fashion in the shock-absorbing liner at a surface opposed to the shell. With the helmet having such a structure, the air duct cannot be clogged with wearer's hairs, leading to a good ventilation, as compared with the helmet having an air duct provided in the shock absorbing liner at an inner surface, that is, a surface opposed to the wearer's head.
However, it has been found that the ventilating ability of such helmet, in practice, may be lower against expectation, which is due to the following reason.
Shell of helmets is made of FRP in recent years and has an inner surface which is crude due to the exposure of a reinforcing fiber. For this reason, there are fine clearances in anywhere between the shell and the shock absorbing liner, and if these clearances come into communication with the air duct, air-stream leaks out from the air duct and the flow rate thereof is reduced in the air duct, resulting in a degraded ventilative ability.